Drilling motors used at the lower end of drill strings to drive drill heads are well established in the art. Most such motors are powered by the drilling mud forced down the drill string bore but some are electric powered. Drilling motors commonly have output shafts to accept the drill head and such shafts are constructed and supported to accept the shock of movement along the well bore as well as the normal drilling loads applied to the drill head, or drill bit. The power producing rotor is usually constrained radially by the associated housing. If the rotor can accept some axial position change, it is prudent to use the robust output shaft to accept axial forces experienced by the rotor. If the rotational axis of the rotor is subject to mis-alignment from the rotational axis of the output shaft the connection between the two must be effectively flexible. In mud driven motors the rotor is occasionally urged upward by reverse circulation and the coupling must accept tension forces. When the drilling mud is moving downward the coupling must accept the resulting compression forces.
Historically, flexible motor couplings have been the critical factor in determining motor drilling life. Jaw couplings are in common use in drilling motors. It is the means to cope with the axial forces transmitted through the jaw couplings that appears to be the weakening factor. The primary points of novelty of this invention relate to the axial force bearing combination that limit the jaw coupling features to transmitting only rotational effort. To the extent that the jaw coupling features are adapted to cooperate with the axial force bearing elements, those adaptations are also part of the novel features herein disclosed.
Most mud powered drilling motors in current use have rotors that orbit a centerline and rotate about an axis that is somewhat displaced from that centerline. To connect the orbiting rotor to an output shaft that is rotating about a fixed centerline, two flexible couplings are needed that are axially spaced by a connecting intermediate shaft. The coupling of this invention can serve as either one or both such couplings. Some drilling motors have non-orbiting power rotors, electric motors and turbines for instance, housed in bent bodies for directional control. These motors have rotors and output shafts that rotate about intersecting axes and need flexible couplings such as that of this invention.
Motor rotors normally terminate in shaft-like ends for attachment of connecting features and, for the purpose of this application, may be referred to as shafts or machine members.
It is therefore an object of this invention to provide a flexible motor coupling of simple and durable construction that can accept forces in both axial directions.
It is another object of this invention to provide a flexible motor coupling that carries axial forces on expendable elements removable from the torque conducting elements.
It is yet another object of this invention to provide a flexible motor coupling with axial force carrying elements that define the points of intersection of axes of rotation of the connected rotating members.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached claims and appended drawings.